KR20070095982A - Shaped direct chill aluminum ingot - Google Patents

Abstract

Method and apparatus for forming aluminum ingot having shaped ends to avoid alligatoring during rolling.

Description

Shaped direct chill aluminum ingot

This application claims priority to US Provisional Application No. 60 / 639,210, filed Dec. 27, 2004, which is incorporated herein by reference.

FIELD OF THE INVENTION The present invention relates to aluminum ingot casting, and more particularly to aluminum ingots having shaped ends.

In the case of vertical casting of aluminum ingots, shallow depressions remain in the upper end of the ingot due to shrinkage during solidification. The bottom of the ingot is flat. In ingot rolling, the surface layer in contact with the roll of the ingot deforms more than the inner layer. This results in a shallow depression in the upper end and a flat lower end when the ingot is rolled in a reversing mill. Accordingly, there is a problem that the depression is formed at the end of the rolled material in the industry, what is called "alligator" type split. Even if the depression at the top of the diarrhea is removed, an alligator separation is still formed due to the nature of the rolling. The alligator separator must be removed and the scrap thereby becomes an important factor in determining the recovery rate of the ingot. If the depression is not removed, machining problems can occur in subsequent lines. Therefore, there is a great need for a method and apparatus for solving the above problems in order to improve the recovery of metal from the ingot.

In the past, several methods have been used to solve this problem. For example, US Pat. No. 6,453,712, which discloses a method and apparatus for reducing crop loss in slab and ingot rolling, forms or forms a butt end in a special shape and optionally also forms an upper end. It is about manufacturing a slab ingot. Said special shape is formed by machining, forging, preferably casting. The special shape of the lower end is imparted by the specially formed lower block or starter block at the time of casting. A special shape of the bottom block is given to the bottom of the casting ingot. The specially shaped lower end of the slab forming ingot is generally rectangular in shape and has an extension extending outward in the longitudinal direction and this part is inclined downward toward the recessed central valley area. The extended end and the sides of the recessed valley area have parallel extending, tapered or curved edges. Similar shapes can be imparted to the top of the ingot by using a specially shaped hot top mold at the end of the casting run, or by machining or forging the molded top. On subsequent hot rolling in a reversing roughing mill, this specially shaped slab ingot minimizes the formation of overlaps and tongues, thereby reducing end crop losses and improving material recovery. The efficiency of the rolling mill is improved by improving the metal throughput of the rolling mill.

U. S. Patent No. 4,344, 309 discloses a process comprising a slab rolling method, in which a recess in the thickness direction is formed on a pair of opposite surfaces of each of the upper and lower ends of the steel ingot, Rolling a central portion not yet rolled by the depth of the recess, then forming a recess in the width direction at the same end as described above, and rolling a central portion not yet rolled by the depth of the width d recesses; The reduction value in the thickness direction is ΔH _T , and the reduction value in the width direction is ΔH _W. When the material is relatively large and the side profile of the material shows double barreling, the ΔH _W / ΔH _T is adjusted from 0.40 to 0.65, the material thickness is relatively small, and the side shape of the material is a single barrel. In the case of, the ΔH _W / ΔH _T is adjusted to 0.3 or less; Fishtails are prevented from growing to reduce crop losses due to overlap of fishtail and double plate shapes, thereby significantly improving the rolling yield.

U. S. Patent No. 4,587, 823 discloses an apparatus and method which enables semi-continuous rolling of a wide range of product widths starting from less than three times the slab width. The tip of the slab is laterally upset between the forged or tapered die so that the width of the tip gradually decreases to a value smaller than the desired width at the end of the pass. The slab is then passed through grooved vertical edging rolls to reduce its width and enter the roll of the roughing stand. Edge rolling moves the overfilled metal into the voids formed by the die. When the tail end of the slab approaches the ripping stand, the edge roll retracts to allow the end of the slab to extend laterally. As the slab leaves the roughing stand, it is rolled between grooved vertical edge rolls to reduce spreads and to scale the extended tail end. Such manipulation causes the tail end to swell backwards from its center to compensate for fishtailing. The roughing stand is then reversed and the slab is rerolled in the opposite direction in the same way.

U. S. Patent No. 1,603, 518 discloses a rolling process to avoid ears or cupped ends. The method provides an ingot with a predetermined end dimension, and the heating or depth of reduction of the ingot is predetermined in relation to the end dimension so that an effective extrusion force is exerted over the entire end area. The end face is moved almost uniformly with respect to the ingot body.

U. S. Patent No. 4,608, 850 discloses a method of operating the mill in a manner that avoids alligator separation from occurring as the thickness of the metal slab decreases in the mill. The slab follows the schedule of repeated passes as it passes through the mill and a predetermined amount of thickness reduction occurs in each pass. The method includes analyzing a pass schedule of such a slab, noting any pass on the schedule with an entry gauge and a reduction draft that may cause the alligator separation of the slab to be generated. . The non-tapered nose of the slab is provided in the mill bite, and if the combination of the entry gauge and the reduction draft does not cause the alligator separator to generate, the slab is reduced in thickness as scheduled through the mill. However, if the combination of the entry gauge and the reducing draft is or tends to cause slab alligator, then the method can be changed to a combination of an antique gauge and a reducing draft that does not cause alligatoring. change the size of the working gap). The nose of the slab is then guided to the bite of the rolling mill with the changed working gap and once the slab nose enters the bite of the rolling mill, the working gap of the rolling mill is returned to a size that can achieve the planned slab thickness reduction.

U. S. Patent No. 4,593, 551 discloses a method of reducing the thickness of a metal slab under conditions that are prone to alligator defects. The method consists in tapering at least one end of the slab and guiding it to the rolling mill. The tapered end is reduced in thickness inside the rolling mill, and the decrease is increased as the tapered end is passed through the rolling mill. The slab is continued through the rolling mill and its thickness is reduced. The ends of the slabs are tapered again and guided back to the rolling mill, each of which provides a combination of inlet thicknesses to the thickness reduction, in which the reduction taken in each tapered area does not produce alligator at the slab end. To be The non-tapered remainder of the slab is reduced in thickness to the inlet thickness of the thickness reduction area where alligators tend to form in the rolling mill.

U. S. Patent No. 4,387, 586 provides a method and apparatus for rolling a rolled material in its width direction. The flat metal-shaped rolled material may be a slab having a large width relative to the thickness thereof, the longitudinal end of which has a gradually decreasing width going to the end of the rolled material by compression when the rolled material is at rest. A portion having a uniform width is formed subsequent to the gradually decreasing width. Thereafter, the rolled material undergoes rolling in the width direction, whereby the fish tail generated at the end of the rolled material is greatly reduced.

However, despite the above, there is a great need for an economical process and apparatus that solves the problem of alligator separation to improve the recovery of metal from the ingot and reduce scrap.

It is an object of the present invention to improve the recovery of rolled metal from ingots.

Another object of the present invention is to provide a novel method of casting an ingot.

It is a further object of the present invention to provide a novel shaped ingot end during casting so as not to form an alligator separator during rolling.

It is another object of the present invention to provide a novel bottom block for casting molten aluminum.

It is still another object of the present invention to provide a new end shape to the ingot which can reduce or prevent the end splitting in the process of rolling the ingot thinly.

These and other objects will become apparent from the accompanying drawings and the description and claims.

In accordance with the above object, an aluminum ingot rolling method for preventing the alligator separation in the process of producing a slab or sheet by reducing the thickness by rolling the aluminum ingot in a rolling mill passing through a multi-stage rolling pass is disclosed. The method includes providing a rolling mill and providing an ingot to be rolled. The ingot has opposing faces to be rolled and at least one molded end. The shaped crucible end has a tapered portion, the taper being in the rolling direction, extending into the thickness of the ingot and extending toward the ingot end, ranging from 2 ° to 20 ° from the rolling surface. The shaped end has an outwardly curved or outwardly rounded surface continuous with the tapered surface, the curved to rounded surface extending across the rolling direction to provide a shaped end. The ingot is reduced in thickness and extended in length through the multi-stage rolling pass of the mill, resulting in a slab or sheet without an alligator separator.

The invention also includes a method of producing an aluminum ingot having a shaped end to prevent alligator separation in a rolling and reducing thickness in a rolling mill passing through a multistage rolling pass. The method includes providing a casting machine for aluminum ingot casting. The casting machine has a square shaped mold and a bottom block to start casting an ingot having a molded end fitted therein. The bottom block has an upper surface for receiving molten aluminum, the upper surface tapering inward toward each other and having rounded ends to provide shaped ends on the casting ingots for rolling. After casting, the casting ingot has at least one molded end. The shaped end includes two sides tapered inwardly towards the end, the taper ranging from 2 ° to 20 ° from the rolling surface while crossing the rolling direction. The shaped end additionally has an outwardly curved or convex surface adjacent to the tapered surface, the curved surface extending across the rolling direction to provide a shaped end. Molten aluminum is provided to cast the ingot. The casting ingot is subjected to the multi-stage rolling pass of the rolling mill to reduce its thickness and extend its length to produce slabs or sheets without alligator separators.

The invention also includes a specially shaped bottom block for producing shaped ingots that minimize alligator separation in subsequent rolling processes. Adjusting the shape of the ingot end according to the invention greatly reduces the generation of scrap during rolling. Furthermore, at the end of casting, an upper mold may be used to form a molded end on top of the ingot.

1 is a cross-sectional view showing a device for casting molten aluminum into an ingot.

2 shows the end of a conventional aluminum ingot.

3 and 4 show an end of an aluminum ingot according to the invention.

5 and 6 is a view showing a 55% reduction after deformation by hot rolling the ingot of FIGS.

7 and 8 show the ingot of FIGS. 2 to 4 after 80% reduction deformation by hot rolling.

9 is a photograph of two rolled samples.

10 is a photograph showing the deformation after the 55% reduction of the two rolled samples of FIG.

Figure 11 is a photograph showing the deformation after the 80% reduction of the two rolled samples of FIG.

12 is a cross-sectional view showing an end portion of an ingot having a 10 ° taper.

Fig. 13 is a sectional view showing an end portion of an ingot having a 15 ° taper.

14 is a sectional view of the end of an ingot having a 20 ° taper;

Referring to FIG. 1, a preferred embodiment of the present invention for casting aluminum ingots is shown. In FIG. 1, a holding furnace 10 containing molten aluminum 12 is shown. Molten aluminum may pass through the filter box 14 to remove the fine particles. The molten aluminum is then refined through the retrofit rod 16 to enter the molten metal pool 17 in the mold 20 where it solidifies into a solid ingot 22 where the solid ingot 22 is attached to the bottom block 24. Is supported by. The lower block 24 descends to match the solidification speed of the pool 17. Bottom block 24 is shown to have a cross-sectional structure in accordance with the present invention.

In conventional ingot casting, the end 30 (FIG. 2) of the ingot is almost flat so that little curvature is provided at the ingot end. The ingot has a large, flat top and bottom surface and the bottom surface is almost parallel to the top surface. However, as noted here, during rolling, the surface layer undergoes severe deformation compared to the deeper layer, so that the upper and lower surfaces of the ingot are longer than the inner side of the conventional ingot. Thus, for example, as shown in FIG. 5, when rolling a conventional ingot, the upper layer 34 and the bottom layer 36 of the metal extend further than the inner to middle layers 38 of the metal. This problem may be worsened depending on the rolling amount. For example, when the thickness is reduced by 80% by hot rolling, as shown in Fig. 7, the upper layer 34 and the bottom layer 36 are further extended to form what is called an alligator type separator. Such separators have to be removed, resulting in a large amount of metal scrap. Thus, it will be appreciated that there is a high need for ingots that do not have an alligator separation.

The present invention provides such an ingot. It has been found that the shape of the end of the ingot can be shaped to avoid the formation of an alligator separator. In other words, it has been found that no separation occurs upon rolling at the end of the ingot if the end of the ingot is provided as a curved or rounded end, for example as shown in FIG. 3. The shape is preferably approximately a semicircle that extends along the width A-A of the ingot. As shown in FIGS. 4A-4C, an arc formed at about 10 ° to about 70 ° across the thickness at the ingot end may be used. Also, a taper of 2 ° to 20 ° formed between the upper surface 22A and the lower surface 22B can be used.

In order to explain the present invention, reference is made to FIGS. 9, 10 and 11 which show photographs of slabs before or after rolling. In FIG. 9 two slabs before rolling are shown. The upper slab has a conventional flat end and the lower slab has a rounded end according to the invention. Referring to FIG. 10, an end shape can be seen when each slab is hot rolled to reduce the thickness by 55%. Conventional flat ends express alligator separations, while rounded ends according to the present invention have been reduced in thickness without an alligator separation.

Referring to FIG. 11, it can be seen that in the case of 80% thickness reduction deformation, the conventional slab has more wider alligator separation portion. It can be expected that the separator will extend further into the metal to separate into layers. In comparison, ingots with rounded ends show no alligator separation even at 80% reduction in thickness. As mentioned earlier, the alligator separator must be cut for the utility of the rolled material, so that a significant amount of metal is scraped.

Preferred embodiments are shown in FIGS. 4A-4C. In FIG. 4A a schematic view of an ingot 22 having a molded end in accordance with the present invention is shown. The shaped end is first prepared for providing a taper having a taper between 2 ° and 20 °. In FIG. 4A a 5 ° taper is shown, the taper extending across the width of the ingot to slab across the rolling direction. The taper may extend a distance X (FIG. 4A). The tapered portion ends in the rounded portion 30, and preferably the rounded portion consists of a portion of a circle having a radius R. Radius R depends on the thickness of the ingot or slab. It can be seen that the radius is smaller for larger tapers, for example 15 ° tapers, for ingots of the same thickness.

The end where the ingot is specially shaped can be formed by machining, forging or pressing. However, preferably the shaped end is formed at the time of casting. As noted above, this is achieved by means of a bottom block 24 made of a special shape, for example as shown in FIG. 1, it can be seen that the lower block 24 has a curved to rounded surface 50 and a tapered surface 52. When the molten metal 12 is injected into the mold 20 and immersed in the lower block 24, the molten metal has a shape of an inner surface defined by the faces 50 and 52. The special shape of the top mold for finishing the ingot casting can also be used to shape the top of the ingot. The top mold may be an adjustable hot top mold to an adjustable conventional or EMC mold. As a result, the scrap is significantly reduced during ingot rolling. Alternatively, the top of the ingot may be machined, pressed or forged into a die having the desired shape.

Three ingots 3014 were cast, scalped and then machined to the shape of FIGS. 12-14. The first 10 ° taper 40 was attached to the first ingot, the first 15 ° taper 42 was attached to the second ingot, and the first 20 ° taper was attached to the third ingot. Second portions were machined at the ends of the first, second and third ingots. The second taper 46 is 64 ° horizontal to the first ingot, the second taper 48 is 62 ° to the second ingot, and the second taper 50 is 78 ° to the third ingot. Was provided). It will be appreciated that the first taper may range from 2 ° to 25 ° and the second taper may range from approximately 50 ° or less to approximately 80 °. The ingot was then heated for hot rolling. The ingots were hot rolled from approximately 28 inches thick to 1.2 inches thick without the formation of an alligator separator.

It is possible to hot roll without an alligator separation, reducing scrap and having a useful effect on aluminum rolling.

Claims (29)

In order to prevent the alligator separation in the slab production process by reducing the thickness of the aluminum ingot by rolling in a rolling mill passing through a multi-stage rolling pass, (a) providing a rolling mill; (b) providing an ingot to be rolled having two large flat faces and at least one molded end, the shaped end being (i) opposing faces taper towards the end to form a tapered surface, the tapered surface being provided in the rolling direction and extending towards the end with a range of 2 ° to 20 ° from the rolling surface, (ii) the end portion has a curved surface adjacent to the tapered surface, the curved surface extending across the rolling direction, step; And, (c) reducing the thickness and extending the length of the ingot through a multi-stage rolling pass of the rolling mill to produce a rolled material without an alligator separation part; Aluminum ingot rolling method comprising a. The method of claim 1, wherein the tapered surface is in the range of 5 ° to 15 °. The method of rolling aluminum ingots according to claim 1, wherein the curved surface is almost semicircular. The aluminum ingot rolling method according to claim 1, wherein both ends of the ingot have a tapered surface and a curved surface. The method of rolling aluminum ingots according to claim 1, wherein at least one of both ends of the ingot is formed at the time of casting from a shape of a lower block in which aluminum is poured thereon at the time of casting. The method of rolling aluminum ingots according to claim 1, wherein at least one end of the ingot is formed by machining after the ingot is made. The method of rolling aluminum ingots according to claim 1, wherein both ends of the ingot are molded in casting to provide the molded end. A method of producing an aluminum ingot having a shaped end to prevent alligator separation in a process of rolling down an aluminum ingot in a rolling mill passing through a multi-stage rolling pass to reduce thickness, (a) providing an aluminum ingot casting casting machine having a square-shaped mold and a bottom block fitted therein which starts casting the ingot having the shaped end, the lower block having an upper surface for receiving molten aluminum. Wherein the top surface is tapered inwardly toward each other and has a rounded end to provide a casting ingot for rolling, the casting ingot having at least one molded end, wherein the molded end is (i) opposing faces taper towards the end to form a tapered surface, the tapered surface being provided in the rolling direction and extending towards the end with a range of 2 ° to 20 ° from the rolling surface, (ii) the end portion has a curved surface adjacent to the tapered surface, the curved surface extending across the rolling direction, step; (b) providing molten aluminum to be cast into an ingot; (c) casting the ingot; (d) reducing the thickness and extending the length of the ingot through a multi-stage rolling pass of the rolling mill to produce a rolled material without an alligator separation part, Aluminum ingot production method having a molded end comprising a. 10. The method of claim 8, wherein the tapered surface has molded ends that range from 5 [deg.] To 15 [deg.]. The method of producing an aluminum ingot as recited in claim 8, wherein the curved surface has a shaped end that is approximately semicircular. The method of claim 8, wherein both ends of the ingot have molded ends having tapered and curved surfaces. 9. The method of claim 8, wherein both ends of the ingot are molded at the time of casting to have shaped ends that provide the shaped ends. A method of producing an aluminum ingot having a shaped end to prevent alligator separation in a process of rolling down an aluminum ingot in a rolling mill passing through a multi-stage rolling pass to reduce thickness, (a) providing molten aluminum to be cast into an ingot; (b) providing an aluminum ingot casting casting machine having a square-shaped mold and a bottom block fitted therein which starts casting the ingot having the shaped end, the lower block having an upper surface for receiving molten aluminum. Wherein the top surfaces are tapered inward toward each other and have a rounded end to provide a casting ingot for rolling; (c) casting the ingot to have at least one molded end, the shaped end being (i) opposing faces having a taper in the range of 2 ° to 20 ° provided in the rolling direction, (ii) having a rounded surface formed adjacent to the tapered surface and extending across the rolling direction Casting; (d) passing the ingot through a multi-stage rolling pass of the rolling mill to reduce the thickness and extend the length to produce a slab without an alligator separation, Aluminum ingot production method having a molded end comprising a. The method of claim 13, wherein the round face has a molded end that consists of a semicircle. The method of claim 13, wherein the tapered surface has molded ends that range from 5 ° to 15 °. An apparatus for producing an aluminum ingot having a shaped end to prevent alligator separation in a process of rolling down an aluminum ingot in a rolling mill passing through a multi-stage rolling pass to reduce thickness, Inserted into a square mold to start ingot vertical casting, (i) has a top surface which receives molten aluminum and on which molten aluminum solidifies; (ii) the upper surfaces are tapered inwardly toward each other and end in a rounded section, having a taper in the range of 2 ° to 20 ° provided in the rolling direction of the ingot. The bottom block, Aluminum ingot production apparatus having a molded end, characterized in that it comprises. 17. The apparatus of claim 16, wherein the rounded portion has a molded end that consists of a semicircle. In order to prevent the alligator separation in the slab production process by reducing the thickness of the aluminum ingot by rolling in a rolling mill passing through a multi-stage rolling pass, (a) providing a rolling mill; (b) two large flat surfaces and opposing faces taper towards the end to form a tapered surface, the tapered surface being provided in the rolling direction and extending toward the end with a range of 2 ° to 20 ° from the rolled surface. Providing an ingot having at least one shaped end configured; And, (c) reducing the thickness and extending the length of the ingot through a multi-stage rolling pass of the rolling mill to produce a rolled material without an alligator separation part; Aluminum ingot rolling method comprising a. 19. The method of claim 18, wherein the tapered surface is in the range of 5 degrees to 15 degrees. 19. The method of claim 18, wherein both ends of the ingot are tapered. 19. The method of rolling an aluminum ingot of claim 18, wherein at least one of both ends of the ingot is formed at the time of casting from the shape of a lower block into which aluminum is poured upon casting. The aluminum ingot rolling method according to claim 18, wherein a second tapered surface extends from the tapered surface. 23. The method of claim 22, wherein the second tapered surface is provided in the range of 50 degrees to 80 degrees. A method of producing an aluminum ingot having a shaped end to prevent alligator separation in a process of rolling down an aluminum ingot in a rolling mill passing through a multi-stage rolling pass to reduce thickness, (a) providing an aluminum ingot casting casting machine having a square-shaped mold and a bottom block fitted therein which starts casting the ingot having the shaped end, the lower block having an upper surface for receiving molten aluminum. Wherein the upper surface has a taper formed inwardly toward each other and forms an end to provide a casting ingot for rolling, the casting ingot having at least one molded end, wherein the molded end is (i) opposing faces taper towards the end to form a first tapered surface, the tapered surface being provided in the rolling direction and extending towards the end with a range of 2 ° to 20 ° from the rolling surface, (ii) said end having a second tapered surface adjacent said tapered surface, said second tapered surface extending in a rolling direction to provide said shaped end step; (b) providing molten aluminum to be cast into an ingot; (c) casting the ingot; (d) reducing the thickness and extending the length of the ingot through a multi-stage rolling pass of the rolling mill to produce a rolled material without an alligator separation part, Aluminum ingot production method having a molded end comprising a. 25. The method of claim 24, wherein the first tapered surface has molded ends that range from 5 degrees to 15 degrees. 25. The method of claim 24, wherein the second tapered surface has molded ends that range from 50 ° to 80 °. 25. The method of claim 24, wherein both ends of the ingot have molded ends that are molded in casting to provide the molded ends. As a casting ingot for rolling into a flat product, (a) opposing faces having a taper in the range of 2 ° to 20 ° provided in the rolling direction; And, (b) a round face continuous to the taper and extending across the ingot, Having at least one molded end consisting of: Casting ingots. As a cast aluminum ingot, (a) opposing faces formed towards the end and provided in the rolling direction and having a first taper extending toward the end in a range of 2 ° to 20 ° from the rolling surface; And, (b) a second taper formed in the rolling direction subsequent to the first taper, Having at least one molded end consisting of: Cast aluminum ingot.

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